http://www.france-property-and-information.c
om/metric-system-and-history.htm - This site
explains the history of the metric system
including key dates and metric conversion
links.
http://www.worldwidemetric.com/metcal.htm -
Here you will find conversion calculators for
length, weight, pressure, volume, and
temperature, just enter in what you know and
push the calculate button to convert to the
unknowns.
http://lamar.colostate.edu/~hillger/laws/ -
Lists and defines the U.S. laws associated
with the metric system.